Shifting the power from a CEO to an instance admin is a massive improvement.
One has autocratic control over the entire site, potentially hundreds of millions of users, investors breathing down their neck, server infrastructure, and other systemic pressures; meanwhile, a fediverse instance admin has autocratic control over nothing but their own instance, a few thousand users at most, with the only money and hardware involved being their own.
The fediverse is incredibly more horizontal and decentralized than any corporate social media, the improvement is massive. And i’m a believer that vertical structures and concentrations of power are at the root of a lot of problems in society, so this is gravy to me.
But yes, it’s worth remembering that it’s not completely decentralized, and admins still have absolute power over their instance. My Mastodon instance admin doesn’t want us to use the name GIMP to refer to the open source image manipulator; they say “gimp” is a slur aimed at disabled people, which i’ve never heard before in my life.